The Sr-poor part of the Sr–{Pd,Pt}–{Si,Ge} systems: Phase equilibria and crystal structure of ternary phases

Abstract

Phase relations have been established by electron probe microanalysis (EPMA) and X-ray powder diffraction (XPD) for the Sr-poor part of four ternary systems: Sr–{Pd,Pt}–Si at 900°C and Sr–{Pd,Pt}–Ge at 700°C. In the Sr–Pd–Si system the formation of the silicide SrPdSi3 (BaNiSn3-type) was confirmed and a small homogeneity region was found. Furthermore, two novel compounds were detected and their crystal structure was refined from X-ray powder patterns: SrPd0.3Si1.7 (AlB2-type) and SrPd5.9Si6.1 (own-type). In the Sr–Pt–Si ternary system a novel compound with AlB2-type was discovered (SrPt0.3Si1.7), whereas SrPtSi3 with the BaNiSn3-type was confirmed. Two more compounds were detected by EPMA, but their crystal structure remains unknown. In the Sr–{Pd,Pt}–Ge systems no new compounds were observed, but the existence of SrPdGe3 and SrPtGe3 (both adopt the BaNiSn3 structure type), and SrPt4Ge12, crystallizing in the LaFe4Sb12 structure type, was corroborated. For selected ternary silicides the electronic structure was evaluated by DFT calculations.